I've driven one too so I know how it feels.

Mainly these people are complaining about the remote possibility of flooding their motor that has always existed with rotary engines and is simply part of their design and has no real way around it. The other complaints center around the fact that the EPA mileage is something like 18/24 mpg (city/highway) and some people are getting 13 mpg in combined driving. News flash to them, the FD RX-7 was rated at 17/25 and it gets crappy mileage too. The EPA test is not very reliable for rotary engines.

From what I've seen there really aren't that many complaints about it being slower than an S2000 or 350Z. In fact from what I can tell a lot of the people who are complaining cross-shopped it against things like the TSX or the IS300.